This invention relates to a bio-absorbable cartilage repair system for regenerating articular cartilage and, more particularly, a system which allows for vascular invasion and cellular migration between the system and the adjacent healthy area of articular cartilage and cancellous bone, thereby resulting in regeneration of the damaged articular cartilage. More specifically, the present invention relates to a method of surgically implanting such a bio-absorbable cartilage repair system and to apparatus useful therein.
Articular cartilage on the surface of bones in joints, most particularly the knee and hip joints, is susceptible to deterioration caused by injury or disease. This deterioration of cartilage leads to pain and eventually loss of joint movement and severe pain. As a result, various methods have been developed to treat and repair damaged or destroyed articular cartilage.
Prosthetic devices are often used to replace damaged or destroyed articular cartilage. For example, U.S. Pat. No. 4,627,853 discloses prosthesis which are used for articular cartilage replacement. The prosthesis are prepared by demineralization of a bone segment, the demineralized bone segment serving as a replacement for articular cartilage.
U.S. Pat. No. 4,880,429 discloses a prosthetic meniscus which is implanted in the knee. The prosthetic meniscus acts as a scaffold for regrowth of native meniscal tissue, and comprises collagen fibers interspersed with glycoaminoglycan molecules.
U.S. Pat. No. 5,176,710 discloses a prosthesis for replacing bone material on the articulating surface of a joint. The prosthesis has a specific modulus of elasticity so as to confer stiffness to the prosthesis, and contains concave shapes which are suitable for biologic ingrowth.
U.S. Pat. No. 4,502,161 discloses a prosthetic meniscus which replaces the natural meniscus between the articular surfaces of the bones and the joints, and comprises an insert and extension for attachment to the bone and a reinforcing fabric or mesh embedded therein.
U.S. Pat. No. 3,745,590 discloses a prosthesis for the repair or replacement of joints, which prosthesis comprises a body portion, including a stem and ligamentous elements, and allows for tissue ingrowth.
U.S. Pat. No. 5,123,927 discloses a knee prosthesis comprising bone cement containing an antibiotic.
Although there are several prosthetic devices which can be used in the replacement of damaged or destroyed articular cartilage, prosthetic devices have several disadvantages. For example, cements which are used to attach prosthetic devices to bones may loosen and eventually fail. In addition, fragmented cement can move into the joints and associated lymph tissue and cause inflammation and further damage. Further, cements result in the formation of fibrous tissue between the bone and the prosthesis. Another major disadvantage associated with the use of prosthesis is that the prosthetic device may be larger than the damaged cartilage that needs to be replaced, thereby requiring removal of portions of healthy bone and/or cartilage in order to accommodate the prosthetic device. Hence, the need remains for a system for repairing and regenerating articular cartilage which avoids the problems associated with prosthetic devices.
Another means used to treat damaged articular cartilage is the placement of repair pieces onto the bone, which repair pieces substitute for cut-out pieces of cartilage. For example, U.S. Pat. No. 5,067,964 discloses an articular cartilage repair piece which comprises a layer of non-woven, felted fibrous material which is limp and readily conformable to flat and curved surfaces. The articular cartilage repair piece is attached to the bone, for example, by bio-absorbable screws or pins or like temporary fixation techniques. Fibrous tissue ingrowth eventually surrounds the repair piece, thereby causing the repair piece to be permanently attached to the bone. Although U.S. Pat. No. 5,067,964 discloses an alternative method for repairing damaged articular cartilage, it does not disclose any means or method of regenerating damaged or destroyed articular cartilage.
Quite recently, a system for regenerating damaged or destroyed articular cartilage, wherein the regenerated articular cartilage is functionally similar to non-damaged articular cartilage, has been developed. Unfortunately, the method of surgically implanting the system assembly using the conventional tools available to the surgeon is both time consuming and laborious. In addition, where the damaged articular cartilage is of sufficient size to require the surgical implantation of a plurality of the system assemblies rather than just one, the several assemblies should be placed in appropriate juxtaposition relative to one another and to the periphery of the undamaged articular cartilage surrounding the injury. It can be difficult, especially for the inexperienced surgeon, to rapidly and accurately place the several assemblies in appropriate relative locations.
Accordingly, an object of the present invention is to provide a method of surgically implanting a system for regenerating articular cartilage.
Another object is to provide such a method which is relatively fast and easy to perform, even for a surgeon with limited experience in this method.
A further object is to provide in one embodiment such a method involving the placement of a plurality of repair assemblies which utilizes apparatus for determining the placement of one repaired assembly relative to another.
It is another object of the present invention to provide such a method which facilitates a three dimensional approximation of the original surface of the articular cartilage.